Electrode for use in electrothermal processes.



B. B. JEWETT. ELEGTRQDE FOR USE IN ELEGTR-OTHERMAL PROCESSES. APPLIGATION TILED PBB.14,1912.

1,667,031, Patented July 8,1913.

an, j 0 v) @273; i WM m R War honaceous necessary to place a through it UNITE strarns PATENT OFFICE ELMER B. ,JEWETT, or cL RKsBURG, wss'r VIRGINIA, Assrenoa 'ro NATIONAL cansoigcolyiran r, OF'CLEVELAND, OHIO, a conronarxon or NEW JERSEY.

ELECTRODE FOR USE I ELECTROTHERMAL PROCESSES.

Specification of Letters Patent. Applicationfiled February 14, 19 12.

ing which has heretofore attended such uses of ord nary carbon electrodes.

I n electrothermal processesit is frequently cold electrode in a hot turn-ace, or to withdraw a hot electrode. Either of these operations. causes disruptive stresses in the electrode owing to the more rapid expansion or contraction of the sur-' This stress is a face than of the center. function of the furnace-temperature, the heat conductivity of thematerial, the coetlicient of expansion of the material, and It varies di reetly as the furnace temperature and the diameter of the electrode, and as the coetlicient of expansion of the material. With small electrodes or larger ones of high heat conductivity, breakage due to such stresses is inappreciable, but with large electrodes ,of fine grain and low heat conductivity the stress is often. sufficientto cause cracks which deepen with alternate heating and) cooling of the electrode until-breakage occurs.

This invention is an electrode which dif- -fers from the ordinary carbon electrodes previously used in that it has, distributed as evenly aspossible, lumps or relatively large particles of earbon or can material, such, for example, as electrodescrap, anthracite coa-l'or coke, said included lumps or particles being of such size and strength as are necessaryto prevent the formation or spreading ofcracks,

such as are commonly caused by the before mentioned stresses. It is impossible to state with exactness the relative or volume of such included lumps.- Bnt these facts must be taken into account. large'in diameter, or if their volume be relatively too large, the electrode will lose in'strength. If they are too small or too few, the purpose for which they are employed will .not

Harrison and vdetermining as nearly -should be used in electrodes of various' diamje If they are to be I f they are too.

IatentedJuly 8, 1913-. Serial No. 677,537.

be fully subserved. Also, the larger the electrodesare in diameter,- the larger these included lumps should bea Also, the higher the heat of the furnace in which they are to be used, the largershould be the included lumps. A series of experii ments have been conducted with. a view to as possiblewhat the diameter and what should be the relative volume of these included lumps? LO get the. best results, all things considered. As a resultof those experiments, it is my 7 present belief that about 25 per cent. of the. electrode should be made of theseincludedlumps or particles, the remainder being m composed, as is common, of carbon Hour and f a suitable binder, such aspiteh, I- believe} also that the diameters of the lumps to. be employed with electrodes of diilerent diam-'5. eters should be such as is represented bathe; abseissae of a parabola whose ordinatesare the diameters of the electrodes,- and whose temperature was substant ially" can grade. It is not,.how evcr, my'intent io limit the size of the included particles lumps tojthe sizes whichthis' formula wi r5? indicate. I simply state the'formula, asth best which I now know for determining the; smallest diameters of lumps which Wh in a practical and efficientdegree p the cracking and breaking oi the) electro by the stresses specified. Obviously, h u ever, these included lumps may. large in diameter up. to any size whieh-will notg unduly weaken the electrodes. If they-a smaller, they will, althoughin a less degree, prevent breaking and cracking. the electrodes are to be used in electric f naces wherein the temperature-is tofb higher than 1500 centigrade, the size. ofg 1. these included lumps should be increased}: used in furnaces havin a temperature materially less than 1500.? centigrade, the size ofthese included particlcs may be ClCCYQflSQt In the drawing, Figure. 1 sectional view of an electrode embodying the invention. Fig. 2 is'a side elevation. thereof partly broken away. i i g Referring to the parts by lette s, A;

10.5. is a transverse resents a miirture of carbon flour agglomdistributed throughout its mass relatively crater] by carbonaceous coke, and B reprelarge particles of carbonaceous material subsents the particles of carbonaceous material stantially as and for the purpose specified.

which are distributed throughout the elec- In testimony whereof, I hereunto afllx my '5 trode. signature in the presence of two witnesses. 5 Having thus described my invention, I EI MFR B IEWE-TT claim-1 J An electrode for use in electrothermal Witnesses: processes consisting of carbon flour agglom- CHARLES Long,

:0 erated by a carbonaceous coke, and having JOHN C. LONG. 

